Windows only: Sumatra PDF Viewer is a tiny, quick loading PDF viewer, that can be downloaded as a single executable file for Windows. Unlike the heavy, resource consuming Adobe Reader(with the boring update bug), Sumatra takes less than 2 seconds to launch.
Don’t let its minimalistic design fool you, it opens most PDF files and has numerous keyboard shortcuts such as;
j – scroll by one line
k – scroll back by one line
n – goto next page
p – goto previous page
F3 – find next
F11 – fullscreen
Even though Sumatra PDF Viewer is already very portable for your flash drive, the guys at PortableApps still have their own portable version.
If you want to use Sumatra as the default PDF viewer in Internet Explorer and FireFox, without undoing with Adobe Acrobat, then do this; Launch Sumatra PDF viewer -> Select File/Make Sumatra a default PDF reader -> Launch Adobe Acrobat -> Select Edit/Preferences -> Select Internet -> Un-check “Display PDF in browser” and finally Click OK.